JP2009273094A - Data communication system, data communication terminal, data communication method, and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress the increase of processing burden or the degradation of communication efficiency which are caused in a network or in a transmitting/receiving terminal in accordance with the loss of a confirmation response packet. <P>SOLUTION: On the basis of a confirmation response loss rate relating to a confirmation response packet that is not delivered to a transmitting terminal 10, a data packet loss rate relating to a data packet that is not delivered to a receiving terminal 20 and a target value of a redundant retransmission data packet generation amount or a redundant retransmission data packet generation rate relating to a data packet redundantly retransmitted from the transmitting terminal, from among the data packets delivered to the receiving terminal 20, a confirmation response frequency indicating a frequency to transmit the confirmation response packet to the transmitting terminal 10 is determined and on the basis of the confirmation response frequency, the confirmation response packet to a received data packet is transmitted from the receiving terminal 20 to the transmitting terminal 10. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a packet communication technique, and more particularly to a packet retransmission control technique during packet transfer.

  In packet communication, TCP (Transmission Control Protocol) is widely used as a protocol for guaranteeing the reachability of data packets (see, for example, Non-Patent Document 1). In this TCP, the sending terminal assigns a sequence number to each data packet and transmits it to the receiving terminal. The receiving terminal refers to the sequence number of the received data packet and assigns the sequence number expected to be received next. The acknowledgment packet (ACK) is returned to the transmitting terminal. In the transmission terminal, the arrival of the data packet at the reception terminal can be confirmed by the confirmation response packet from the reception terminal, and the unreachable data packet can be retransmitted from the transmission terminal to the reception terminal.

  When such an acknowledgment packet is returned for each data packet, the overhead associated with the processing operation of the acknowledgment packet is increased in packet communication. For this reason, for example, a delayed ACK technique has been proposed as a technique for returning one acknowledgment packet to a plurality of received data packets at the receiving terminal (see, for example, Non-Patent Document 2). Specifically, when the receiving terminal does not immediately return an acknowledgment packet for the received data packet, a predetermined number of data packets arrive, or after waiting for a certain period of time, the data packet does not arrive ( For example, an acknowledgment packet is returned only when the delayed ACK timer times out. Thereby, the processing operation of the acknowledgment packet can be omitted.

RFC793, http://www.ietf.org/rfc/rfc0793.txt RFC1122, http://www.ietf.org/rfc/rfc1122.txt

  However, in such a related technique, when a loss occurs in the acknowledgment packet, a large amount of data packets are retransmitted from the transmission side, which increases the load on the network and transmission / reception terminals and decreases the communication efficiency. There was a problem.

  That is, in the delayed ACK technique, if the transmitting terminal does not receive an acknowledgment packet for a certain time or longer, it determines that the data packet has been discarded, and retransmits the data packet transmitted after the previously received acknowledgment packet. . FIG. 15 is a sequence diagram showing a data packet retransmission operation when an acknowledgment packet is lost. For example, as shown in FIG. 15, it is assumed that a delay ACK is set on the receiving side so that an acknowledgment packet is returned to the transmitting terminal for every 100 data packets.

  At this time, if the acknowledgment packet returned from the receiving terminal is lost, the transmitting terminal determines that all 100 transmitted data packets are not received by the receiving terminal, and sends the same data packet as the previous transmission. Resend everything. For this reason, if retransmission is performed due to a loss of an acknowledgment packet even though the data packet is received on the receiving terminal side, a load is placed on the network and the transmitting / receiving terminal, and at the same time, the communication efficiency decreases.

  The present invention is for solving such problems, and is a data communication system and data that can suppress an increase in processing load and a reduction in communication efficiency in a network or a transmission / reception terminal, which occur in response to an acknowledgment packet loss. An object is to provide a communication terminal, a data communication method, and a program.

  In order to achieve such an object, a data communication system according to the present invention includes a transmission terminal and a reception terminal connected via a communication network, and the reception terminal receives data packets received from the transmission terminal. Is sent back to the transmitting terminal, and the transmitting terminal retransmits the undelivered data packet according to the reception status notified by the confirmation response packet, and the data is transmitted within a predetermined time from the transmission of the data packet. A data communication system that retransmits all of the data packet when an acknowledgment packet related to the packet does not arrive from the receiving terminal, and the transmitting terminal transmits an acknowledgment packet that has not arrived at the transmitting terminal based on the reception status of the acknowledgment packet The confirmation response loss rate is calculated by calculating the confirmation response loss rate and reporting the confirmation response loss rate to the receiving terminal. A rate calculating unit, and the receiving terminal calculates a data packet loss rate related to a data packet that has not arrived at the receiving terminal based on a reception state of the data packet, and acquires data for acquiring an acknowledgment response loss rate notified from the transmitting terminal Packet loss rate calculation unit, data packet loss rate and acknowledgment response loss rate, redundant retransmission data packet generation amount or redundant retransmission data regarding data packet redundantly retransmitted from transmitting terminal despite reaching to receiving terminal An acknowledgment frequency determination unit that determines an acknowledgment frequency indicating the frequency of acknowledgment packets to be returned based on the target value of the packet occurrence rate, and an acknowledgment that returns an acknowledgment packet to the transmitting terminal based on the acknowledgment frequency Department.

  The data communication terminal according to the present invention includes a transmission terminal and a reception terminal connected via a communication network, and the reception terminal transmits an acknowledgment packet indicating the reception status of the data packet received from the transmission terminal. The transmitting terminal resends the undelivered data packet according to the reception status notified by the acknowledgment packet, and the acknowledgment packet related to the data packet is received within a predetermined time from the transmission of the data packet. In the data communication system that retransmits all of the data packet if it does not arrive from the data communication terminal used as the receiving terminal, the data packet loss related to the data packet that did not reach the receiving terminal based on the reception status of the data packet Rate and the acknowledgment packet notified from the sending terminal. A data packet loss rate calculation unit for obtaining an acknowledgment loss rate, a data packet loss rate and an acknowledgment loss rate, and redundancy related to a data packet that is redundantly retransmitted from a transmitting terminal despite reaching the receiving terminal An acknowledgment frequency determining unit that determines an acknowledgment frequency indicating the frequency of acknowledgment packets to be returned based on the amount of retransmission data packets generated or the target value of the redundant retransmission data packet occurrence rate, and an acknowledgment based on the acknowledgment frequency And an acknowledgment unit that returns the packet to the transmitting terminal.

  The data communication method according to the present invention is a data communication system including a transmission terminal and a reception terminal connected via a communication network, and the reception terminal confirms the reception status of the data packet received from the transmission terminal. The packet is returned to the transmission terminal, and the transmission terminal retransmits the undelivered data packet according to the reception status notified by the confirmation response packet, and confirms the confirmation response regarding the data packet within a predetermined time from the transmission of the data packet. A data communication method for retransmitting all of the data packet when the packet does not arrive from the receiving terminal, where the transmitting terminal loses an acknowledgment response regarding the acknowledgment packet that did not reach the transmitting terminal based on the reception status of the acknowledgment packet The confirmation response loss rate calculation step for calculating the rate and notifying the receiving terminal of the confirmation response loss rate. And the receiving terminal calculates the data packet loss rate related to the data packet that did not reach the receiving terminal based on the reception status of the data packet, and obtains the acknowledgment response loss rate notified from the transmitting terminal. Step, data packet loss rate and acknowledgment response loss rate, and redundant retransmission data packet generation amount or redundant retransmission data related to a data packet that is redundantly retransmitted from the transmission terminal even though the reception terminal reaches the reception terminal An acknowledgment frequency determining step for determining an acknowledgment frequency indicating the frequency of the acknowledgment packet to be returned based on the target value of the packet occurrence rate, and the receiving terminal sends the acknowledgment packet to the transmitting terminal based on the acknowledgment frequency An acknowledgment step for returning.

  Further, another data communication method according to the present invention includes a transmission terminal and a reception terminal connected via a communication network, and the reception terminal receives an acknowledgment packet indicating a reception status of a data packet received from the transmission terminal. In response to the reception status notified by the acknowledgment packet, the transmitting terminal resends the undelivered data packet, and the acknowledgment packet related to the data packet is received within a predetermined time from the transmission of the data packet. A data communication method used in a receiving terminal in a data communication system that retransmits all of the data packets when not received from the receiving terminal, wherein the data packet loss rate calculating unit determines whether the receiving terminal is based on the reception status of the data packets. Calculate the data packet loss rate for data packets that did not reach A data packet loss rate calculation step for acquiring an acknowledgment loss rate related to an acknowledgment packet notified from a receiving terminal, and an acknowledgment frequency determining unit, the data packet loss rate and the acknowledgment loss rate, Nevertheless, an acknowledgment frequency indicating the frequency of acknowledgment packets to be returned is based on a redundant retransmission data packet generation amount or a redundant retransmission data packet generation rate target value regarding a data packet redundantly retransmitted from the transmitting terminal. The confirmation response frequency determining step to be determined, and the confirmation response unit include a confirmation response step of returning an acknowledgment packet to the transmitting terminal based on the confirmation response frequency.

  A program according to the present invention is a program for causing a computer of a data communication terminal used as a receiving terminal of a data communication system to execute each step of the data communication method.

According to the present invention, when the data communication status between the transmitting terminal and the receiving terminal is deteriorated, the frequency of confirmation response is increased to reduce the number of data packets for notifying the reception status with one acknowledgment packet, When the data communication status is improved, it is possible to reduce the frequency of confirmation response and increase the number of data packets for notifying the reception status with one confirmation response packet.
For this reason, when the data communication status deteriorates, the influence of the loss of one acknowledgment packet can be suppressed, and when the data communication status improves, the reception status can be notified efficiently with one acknowledgment packet.

Therefore, it is possible to reliably reduce the number of data packets that are redundantly retransmitted from the transmission terminal in response to the loss of the acknowledgment packet, that is, the number of redundant retransmission data packets, although being received at the reception terminal. .
As a result, it is possible to suppress an increase in processing load and a reduction in communication efficiency in the network or transmission / reception terminal, which occur according to the loss of the acknowledgment packet.

Next, embodiments of the present invention will be described with reference to the drawings.
[First Embodiment]
First, a data communication system according to the first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a block diagram showing a configuration of a data communication system according to the first embodiment of the present invention.

The data communication system in FIG. 1 includes a transmission terminal 10 and a reception terminal 20 connected to a communication network 30, and performs data communication by transmitting data packets from the transmission terminal 10 to the reception terminal 20 via the communication network 30. It is a system to do.
In this data communication system, as a function for guaranteeing the reachability of data packets, one response confirmation packet is received from the receiving terminal 20 for a plurality of data packets transmitted from the transmitting terminal 10 as in the case of the TCP delayed ACK technique. Has the function of returning.

  In the present embodiment, an acknowledgment loss rate related to an acknowledgment packet that did not reach the transmitting terminal, a data packet loss rate related to a data packet that did not reach the receiving terminal, and a redundancy from the transmitting terminal among the data packets that reached the receiving terminal. Determining an acknowledgment frequency indicating the frequency with which the acknowledgment packet should be transmitted to the transmitting terminal based on the redundant retransmission data packet generation amount or the redundant retransmission data packet generation rate target value regarding the data packet to be retransmitted Based on this acknowledgment frequency, an acknowledgment packet for the received data packet is transmitted from the receiving terminal to the transmitting terminal.

[Sending terminal]
Next, the configuration of the transmission terminal used in the data communication system according to the first embodiment of the present invention will be described with reference to FIG.
The transmission terminal 10 as a whole is composed of an information communication device such as a personal computer or a mobile phone terminal. As main functional units, a transmission data storage unit 11, a packet creation unit 12, a packet transmission unit 13, a packet reception unit 14, a retransmission A control unit 15 and a confirmation response loss rate calculation unit 16 are provided.

The transmission data storage unit 11 has a function of temporarily storing transmission data output from an application (not shown).
The packet creation unit 12 creates a transmission data packet by adding a header to the transmission data acquired from the transmission data storage unit 11 and outputs the data packet to the packet transmission unit 13 and prepares for retransmission of the transmission data packet. A function of outputting the data packet to the retransmission control unit 15 and a confirmation response loss rate information packet notified from the confirmation response loss rate calculation unit 16 by adding a header to create a confirmation response loss rate information packet, and a packet transmission unit 13 and a function of outputting to.

At this time, in addition to address information used for packet transfer in the communication network 30, a sequence number for uniquely identifying the transmission order of the data packets is described in the header of the data packet.
In addition, in the header of the confirmation response loss rate information packet, in addition to address information used for packet transfer in the communication network 30, an identifier indicating that the packet is a packet for notification of loss rate information, and an acknowledgment response loss rate A sequence number for uniquely identifying the transmission order of information packets is described.

The packet transmission unit 13 has a function of transmitting the data packet output from the packet creation unit 12 and the acknowledgment response rate information packet, and further the retransmission data packet output from the retransmission control unit 15 to the communication network 30. Yes.
The packet receiving unit 14 has a function of receiving an acknowledgment packet from the communication network 30, a function of notifying the confirmation response loss rate calculating unit 16 of the sequence number described in the header of the received acknowledgment packet, and the acknowledgment packet Is output to the retransmission control unit 15.

The retransmission control unit 15 has a function of temporarily holding the data packet output from the packet creation unit 12, a function of deleting the transmission data packet when reception confirmation of the data packet is recognized, and a reception confirmation. If the data packet is not recognized, it has a function of outputting the data packet to the packet transmitter 13 in order to retransmit the data packet.
For the reception confirmation, the acknowledgment packet received from the receiving terminal 20 is acquired from the packet receiving unit 14, and each transmitted data packet is referred to by referring to the sequence number of each data packet described in the acknowledgment packet. The reception success or failure at the receiving terminal 20 is confirmed.

  Since the acknowledgment packet contains the sequence numbers of the data packets received by the receiving terminal 10 among the data packets transmitted from the transmitting terminal 10, the reception can be confirmed based on these sequence numbers. Therefore, among the data packets temporarily held by the retransmission control unit 15, the data packets that match these sequence numbers are deleted. On the other hand, a data packet having a sequence number not described in the acknowledgment packet is output to the packet transmitter 13 for retransmission. If an acknowledgment packet for the data packet does not arrive even after a certain time has elapsed since the transmission of the data packet, all the data packets temporarily held by the retransmission control unit 15 are sent for retransmission. It is output to the packet transmitter 13.

  Based on the reception status of each confirmation response packet output from the packet reception unit 14, the confirmation response loss rate calculation unit 16 causes a loss such as loss or discard among the confirmation response packets returned from the receiving terminal 20. It has a function of calculating the proportion of acknowledgment packets that have not arrived at the transmitting terminal 10 as an acknowledgment response loss rate, and a function of notifying the packet creation unit 12 of the calculated acknowledgment response loss rate. In this case, the confirmation response loss rate may be calculated for every fixed time or for every fixed number of confirmation response packets.

  FIG. 2 is an explanatory diagram showing a method for calculating the packet loss rate. The loss rate for packets such as acknowledgment packets and data packets is calculated by dividing the number of lost packets by the number of transmitted packets, using the sequence number specific to the packet in the header of the received packet. Calculated by For example, as shown in FIG. 2, it is not possible to confirm reception of 12 packets having sequence numbers 106, 112, 123,. Assume that reception of another packet having a sequence number surrounded by a solid line has been confirmed. In this case, 12 packets out of 100 transmitted packets are lost, and the packet loss rate is 12%.

  Of the functional units of the transmission terminal 10, the transmission data storage unit 11 includes a storage device such as a hard disk or a memory. The packet transmission unit 13 and the packet reception unit 14 are configured by dedicated communication circuit units. Moreover, the packet creation part 12, the retransmission control part 15, and the confirmation response loss rate calculation part 16 are comprised from an arithmetic processing part. This arithmetic processing unit has a CPU and its peripheral circuits, and executes various programs related to data communication by executing the program read from the storage unit (not shown), thereby causing the hardware and the program to cooperate with each other. Realize the part.

[Receiving terminal]
Next, the configuration of a receiving terminal used in the data communication system according to the first embodiment of the present invention will be described with reference to FIG.
The receiving terminal 20 as a whole is composed of an information communication device such as a personal computer or a mobile phone terminal. As main functional units, a packet receiving unit 21, an acknowledgment unit 22, a received data storage unit 23, a packet creation unit 24, a packet A transmission unit 25, a loss rate acquisition unit 26, and a confirmation response frequency determination unit 27 are provided.

  The packet receiving unit 21 notifies the loss rate acquiring unit 26 of a function of receiving a data packet or an acknowledgment loss rate information packet from the communication network 30 and a sequence number described in the header of the received data packet, and the data It has a function of outputting a packet to the confirmation response unit 22 and a function of outputting the received confirmation response loss rate information packet to the loss rate acquisition unit 26.

The confirmation response unit 22 obtains and holds the sequence number described in the header from the data packet output from the packet reception unit 21 and the confirmation response frequency notified from the confirmation response frequency determination unit 27. A function for notifying the packet creation unit 24 of each sequence number held in response, and a function for extracting received data from the data packet output from the packet receiving unit 21 and storing it in the received data storage unit 23 ing.
The reception data storage unit 23 has a function of storing the reception data extracted by the confirmation response unit 22 and outputting it to an application (not shown).

The packet creation unit 24 creates a confirmation response packet in which the sequence number notified from the confirmation response unit 22 is written, and a sequence number for uniquely identifying the transmission order of the confirmation response packet in the confirmation response packet. And a function of giving a header describing address information used for packet transfer in the communication network 30 and outputting it to the packet transmitter 25.
The packet transmission unit 25 has a function of transmitting the confirmation response packet output from the packet creation unit 24 to the communication network 30.

Based on the reception status of each data packet output from the packet receiving unit 21, the loss rate acquiring unit 26 generates a loss such as loss or discard among the data packets transmitted from the transmitting terminal 10 and receives the receiving terminal 20. A function for calculating the ratio of data packets that have not arrived at the terminal as a data packet loss rate, a function for notifying the calculated data packet loss rate to the confirmation response frequency determining unit 27, and a confirmation response loss output from the packet receiving unit 21 It has a function of acquiring the confirmation response loss rate from the rate information packet and notifying it to the confirmation response frequency determination unit 27.
At this time, the data packet loss rate may be calculated every certain time or every certain number of acknowledgment packets. The data packet loss rate calculation method may be calculated based on the packet loss rate calculation method of FIG. 2 described above.

  The confirmation response frequency determination unit 27 includes the data packet loss rate and the confirmation response loss rate notified from the loss rate acquisition unit 26, and the redundant retransmission data packet generation amount or the target value of the redundant retransmission data packet generation rate that is set in advance. That is, a function for calculating an acknowledgment frequency indicating the frequency of acknowledgment packets to be returned from the receiving terminal 20 to the transmitting terminal 10 based on the target redundant retransmission data packet generation amount or the target redundant retransmission data packet generation rate, And a function of notifying the confirmation response unit 22 of the confirmation response frequency.

  Of the functional units of the receiving terminal 20, the received data storage unit 23 includes a storage device such as a hard disk or a memory. Further, the packet receiving unit 21 and the packet transmitting unit 25 are configured by dedicated communication circuit units. Moreover, the confirmation response part 22, the packet preparation part 24, the loss rate acquisition part 26, and the confirmation response frequency determination part 27 are comprised from an arithmetic processing part. This arithmetic processing unit has a CPU and its peripheral circuits, and executes various programs related to data communication by executing the program read from the storage unit (not shown), thereby causing the hardware and the program to cooperate with each other. Realize the part.

Confirmation frequency
Next, the confirmation response frequency calculation process will be described with reference to FIGS. FIG. 3 is an explanatory diagram showing the expected number of received data packets. FIG. 4 is an explanatory diagram showing the expected number of retransmission data packets. FIG. 5 is an explanatory diagram showing the expected number of redundant retransmission data packets.

  The response confirmation packet returned from the reception terminal 20 to the transmission terminal 10 is lost to the transmission terminal 10 due to loss or destruction, and the transmission terminal 10 receives the data packet notified by the response confirmation packet. It may not be confirmed. Therefore, if the acknowledgment packet for the data packet does not reach the retransmission control unit 15 of the transmission terminal 10 even after a certain time has elapsed after the transmission of the data packet, the retransmission control unit 15 temporarily holds it. It has a function to retransmit all data packets.

  For this reason, the data packet to be acknowledged by the response confirmation packet is a data packet that is redundantly retransmitted from the transmission terminal 10, that is, a redundant retransmission data packet, although it is received by the reception terminal 20. . Therefore, when the reception status regarding a plurality of data packets is notified by one acknowledgment packet, the loss of the acknowledgment packet greatly affects the number of redundant retransmission data packets.

In the present invention, the frequency of the acknowledgment response is variably controlled based on the data communication status between the transmission terminal 10 and the reception terminal 20, so that the redundant response included in the data packet retransmitted from the transmission terminal 10 to the reception terminal 20 is used. Retransmission data packets are reduced.
In the following, the redundant retransmission data packet generation amount is introduced as an index for calculating such an optimal acknowledgment frequency.

As shown in FIG. 3, an operation in which the transmission terminal 10 transmits a single data packet and receives one acknowledgment packet from the reception terminal 20 is defined as one round. Therefore, when the number of transmission data packets transmitted in one round is N, the transmission frequency of the acknowledgment packet with respect to the number of data packets, that is, the acknowledgment frequency F _ACK is expressed by the following equation (1).
F _ACK = 1 / N (1)

Here, as shown in FIG. 3, when the data packet loss rate is P _{L_DT} , an expected value of the number of data packets that can be received by the receiving terminal 20 in the round, that is, an expected value N _{RCV of the} number of received data packets is (2)
N _RCV = N × (1-P _{L_DT} ) (2)

On the other hand, as shown in FIG. 4, when all the transmitted data packets are received by the receiving terminal 20, the number of received data packets is equal to the number of transmitted data packets N, and the acknowledgment loss rate is P _{L_ACK} , the round In the data packet received by the receiving terminal 20, the expected value of the number of data packets that cannot be confirmed by the transmitting terminal 10, that is, the expected value N _{RTRNS of the} number of retransmitted data packets is expressed by the following equation (3).
N _RTRNS = N × P _{L_ACK} (3)

Therefore, as shown in FIG. 5, when the number of received data packets is N _RCV , the expected value of the number of retransmission data packets at the transmission terminal 10, that is, the amount of redundant retransmission data packets generated per round N _RDND is given by equation (3) By substituting Equation (2) for N, the following Equation (4) is obtained.
N _RDND = N × (1−P _{L_DT} ) × P _{L_ACK} (4)
Further, the redundant retransmission data packet generation amount N _RDND is expressed by the following equation (5) by substituting N calculated backward from equation (1) into equation (4).
N _RDND = (1−P _{L_DT} ) × P _{L_ACK} / F _ACK (5)

Therefore, the acknowledgment frequency F _ACK necessary for maintaining the target redundant retransmission data packet generation amount per round, that is, the target redundant retransmission data packet generation amount N _RDND , is calculated backward from equation (5). Therefore, it is expressed by the following equation (6).
F _ACK = (1−P _{L_DT} ) × P _{L_ACK} / N _RDND (6)

[Target redundant retransmission data packet generation amount]
Next, a method for calculating the target redundant retransmission data packet generation amount will be described.
A method of estimating the target redundant retransmission data packet generation amount from the past communication result between the transmitting and receiving terminals based on the equation (5) is conceivable. That is, when the average value of the data packet loss rate is P _{L_DT_AVG} , the average value of the acknowledgment loss rate is P _{L_ACK_AVG,} and the average value N _AVG of transmission data packets per round, the target redundant retransmission data packet generation amount N _RDND is expressed by the following equation (7) by substituting equation (1) into equation (5).
N _RDND = (1−P _{L_DT_AVG} ) × P _{L_ACK_AVG} × N _AVG (7)

For the target redundant retransmission data packet generation amount, a fixed value calculated in advance based on past communication results may be used, but the data packet loss rate average value calculated at regular intervals during data communication, The target redundant retransmission data packet generation amount may be sequentially updated during data communication using the average value of the acknowledgment response loss rate and the average transmission data packet number N _AVG . Thereby, even when the data communication status changes, a target redundant retransmission data packet generation amount appropriate for the data communication status at that time can be obtained.

Further, when the data packet loss rate and the acknowledgment response loss rate increase / decrease with a change width equal to or greater than the respective threshold values, the most recent data packet N _AVG in one round in the above formula (7) is used instead of the latest one. The target redundant retransmission data packet generation amount N _RDND may be calculated by the following equation (8) using the number N of transmission data packets in one round. Α is a constant.
N _RDND = (1− _{PL_DT_AVG} ) × _{PL_ACK_AVG} × N × α (8)

  When a failure occurs in a node located on the data communication path between the transmission terminal 10 and the reception terminal 20 and a large amount of data packets are temporarily lost, the data packet loss rate and confirmation response before and after the failure Loss rates can fluctuate significantly. In such a case, the confirmation response frequency rapidly increases and the number of confirmation response packets increases, leading to a rapid increase in processing load on the transmission terminal 10 and the reception terminal 20. Therefore, if the target redundant retransmission data packet generation amount is calculated using the most recent one round of transmission data packet N, the change width of the target redundant retransmission data packet generation amount can be suppressed. A sudden increase in processing load at 20 can be avoided.

  In addition, when the upper limit value and the lower limit value are set as appropriate ranges for the target redundant retransmission data packet generation amount, and the newly calculated target redundant retransmission data packet generation amount is outside the appropriate range consisting of these upper and lower limit values, As the new target redundant retransmission data packet generation amount, an upper limit value or a lower limit value of an appropriate range may be used. As a result, even if the data packet loss rate or the acknowledgment loss rate fluctuates significantly, it is possible to maintain the stable retransmission control because the extreme target redundant retransmission data packet generation amount and the acknowledgment frequency are not calculated. It becomes. At this time, the upper limit value and lower limit value of the confirmation response frequency corresponding to the upper limit value and lower limit value of the target redundant retransmission data packet generation amount are calculated in advance and compared with the newly calculated confirmation response frequency. You may make it suppress the fluctuation | variation of a response frequency.

  Further, the target redundant retransmission data packet generation amount may be calculated according to the number of hops between transmitting and receiving terminals. The number of hops is obtained by the number of nodes plus 1 through which data packets and acknowledgment packets pass in the data communication path between the transmitting terminal 10 and the receiving terminal 20. As the number of passing nodes, that is, the number of hops increases, the data packet loss rate and the confirmation response loss rate may increase due to the influence of other traffic. Therefore, if a function is derived in advance as a rule of thumb from the past communication result, for example, the relationship between the number of hops and the target redundant retransmission data packet generation amount, the data between the transmitting terminal 10 and the receiving terminal 20 The target redundant retransmission data packet generation amount corresponding to the number of hops related to the communication path can be obtained from the above function.

[Operation of First Embodiment]
Next, the operation of the data communication system according to the first embodiment of the present invention will be described with reference to FIGS. FIG. 6 is a flowchart showing the confirmation response frequency calculation process of the data communication system according to the first embodiment of the present invention. FIG. 7 is a flowchart showing an acknowledgment packet transmission process of the data communication system according to the first embodiment of the present invention. FIG. 8 is an explanatory diagram of an example of confirmation response frequency determination processing timing.

First, the data communication operation of the data communication system according to the first embodiment of the present invention will be described with reference to FIG.
The packet creation unit 12 of the transmission terminal 10 acquires transmission data from the transmission data storage unit 11, adds a header for each unit data amount, and outputs the header to the packet transmission unit 13.
The packet transmission unit 13 transmits the data packet from the packet creation unit 12 to the communication network 30.

The packet receiving unit 21 of the receiving terminal 20 receives the data packet from the communication network 30, notifies the loss rate acquiring unit 26 of the sequence number described in the header of the data packet, and sends the data packet to the confirmation response unit 22. Output.
The confirmation response unit 22 acquires the sequence number described in the header of the data packet, notifies the packet generation unit 24 with the frequency notified from the confirmation response frequency determination unit 27, and deletes the header of the data packet. And stored in the received data storage unit 23.
The packet creation unit 24 creates an acknowledgment packet in which the sequence number notified from the acknowledgment unit 22 is described and outputs it to the packet transmitter 25. The packet transmission unit 25 transmits this confirmation response packet to the communication network 30.

The packet receiving unit 14 of the transmitting terminal 10 receives the acknowledgment packet from the communication network 30 and outputs it to the retransmission control unit 15.
The retransmission control unit 15 refers to the sequence number described in the confirmation response packet and deletes the retransmission data packet corresponding to the sequence number. If there is a sequence number for which reception has not been confirmed, a data packet corresponding to the sequence number is output to the packet transmitter 13.
If the acknowledgment packet does not arrive before a certain time has elapsed since the transmission of the data packet, the retransmission control unit 15 outputs all the held data packets to the packet transmission unit 13 and communicates from the packet transmission unit 13. Retransmit to network 30.

Next, the confirmation response frequency determination operation will be described with reference to FIGS.
In response to the arrival of the confirmation response loss rate calculation timing, the transmitting terminal 10 calculates the confirmation response loss rate by the confirmation response loss rate calculation unit 16 in parallel with the data communication operation (step 100). The packet creation unit 12 creates an acknowledgment response rate information packet describing the calculated acknowledgment response loss rate, and transmits the packet from the packet transmission unit 13 to the communication network 30.

The receiving terminal 20 receives the confirmation response loss rate information packet from the communication network 30 through the packet reception unit 14, and acquires the confirmation response loss rate from the confirmation response loss rate information packet through the loss rate acquisition unit 26 (step 101). .
In addition, the receiving terminal 20 receives each data packet output from the packet receiving unit 21 by the loss rate acquiring unit 26 in parallel with the data communication operation according to the arrival of the calculation timing of the data packet loss rate. Based on the above, the loss rate of the data packet is calculated (step 102).

Next, the confirmation response frequency determination unit 27 calculates the confirmation response frequency from the data packet loss rate and the confirmation response loss rate acquired by the loss rate acquisition unit 26 and the preset target redundant retransmission data packet rate. Then, the confirmation response unit 22 is notified (step 103).
Thereafter, the confirmation response unit 22 notifies the packet creation unit 24 of the sequence number of the data packet received by the packet reception unit 21 based on the confirmation response frequency notified from the confirmation response frequency determination unit 27. 24 creates an acknowledgment packet describing the sequence number, and transmits it from the packet transmission unit 13 to the communication network 30 (step 104).

  In the example of FIG. 8, the confirmation response loss rate is calculated every fixed time T1, and the data packet loss rate is calculated every fixed time T2. At this time, since the acknowledgment loss rate is calculated from a plurality of acknowledgment packets, when notifying the reception status regarding a plurality of data packets with one acknowledgment packet, generally T1> T2, It is not limited to. In FIG. 3, every time a new data packet loss rate is calculated, a new acknowledgment frequency is calculated, but at the time when either the acknowledgment loss rate or the data packet loss rate is newly calculated. A new confirmation response frequency may be calculated.

  In the example of FIG. 8, the case where the confirmation response frequency determination process is performed every fixed time T2 has been described as an example. However, the confirmation response frequency determination process is executed every time a certain number of data packets are received. Alternatively, the confirmation response frequency determination process may be executed when the data packet loss rate or the confirmation response loss rate changes by a certain value or more.

Next, an acknowledgment packet transmission process will be described with reference to FIG.
The confirmation response unit 22 of the receiving terminal 20 obtains the confirmation response frequency from the confirmation response frequency determination unit 27, and calculates the number of standby packets until the next transmission of the confirmation response packet, for example, based on the above-described equation (1). (Step 110).
Subsequently, based on the sequence number of the data packet output from the packet receiving unit 21, the confirmation response unit 22 calculates the number of transmission packets of the data packet transmitted after the data packet notified in the previous confirmation response packet (step 111).

  Here, when the number of transmitted packets reaches the number of waiting packets (step 112: YES), the sequence number held so far is notified to the packet creation unit 24. In response to this, the packet creation unit 24 creates a new acknowledgment packet and transmits it from the packet transmission unit 25 to the transmission terminal 10 (step 113).

[Effect of the first embodiment]
As described above, in the present embodiment, the acknowledgment loss rate related to the acknowledgment packet that did not reach the transmitting terminal, the data packet loss rate related to the data packet that did not reach the receiving terminal, and the transmission of the data packets that reached the receiving terminal Based on the target value of the redundant retransmission data packet generation amount regarding the data packet that is redundantly retransmitted from the terminal, an acknowledgment frequency indicating the frequency with which the acknowledgment packet should be transmitted to the transmitting terminal is determined. Based on the frequency, an acknowledgment packet for the received data packet is transmitted from the receiving terminal to the transmitting terminal.

As a result, when the data communication status between the transmitting terminal and the receiving terminal deteriorates, the acknowledgment frequency is increased, and the number of data packets for notifying the reception status with one acknowledgment packet is reduced. Can improve the frequency of confirmation response, and increase the number of data packets for notifying the reception status with one confirmation response packet.
For this reason, when the data communication status deteriorates, the influence of the loss of one acknowledgment packet can be suppressed, and when the data communication status improves, the reception status can be notified efficiently with one acknowledgment packet.

Therefore, it is possible to reliably reduce the number of data packets that are redundantly retransmitted from the transmission terminal in response to the loss of the acknowledgment packet, that is, the number of redundant retransmission data packets, although being received at the reception terminal. .
As a result, it is possible to suppress an increase in processing load and a reduction in communication efficiency in the network or transmission / reception terminal, which occur according to the loss of the acknowledgment packet.

[Second Embodiment]
Next, a data communication system according to the second embodiment of the present invention will be described with reference to FIG. FIG. 9 is a sequence diagram showing a data communication operation of the data communication system according to the second embodiment of the present invention.

  In the first embodiment, an example is described in which one acknowledgment packet is returned for each round, and the reception status of all data packets received in the round is individually notified by one acknowledgment packet. did. In the present embodiment, a case will be described as an example in which a plurality of confirmation response packets are returned in one round and data packets that can be continuously received from the start of data communication are notified each time with these confirmation response packets.

  As shown in FIG. 9, in this embodiment, n (n is an integer of 2 or more) data packets are sequentially transmitted from the transmission terminal 10, and m (m is an integer of 1 ≦ m ≦ n) for these blocks. A series of processing operations of sequentially returning a number of acknowledgment packets from the receiving terminal 20 is defined as one round. Therefore, the acknowledgment packet is returned from the receiving terminal 20 to the transmitting terminal 10 every n / m data packets. In consideration of the loss of the data packet, a timer for generating an acknowledgment packet is provided in the acknowledgment unit 22 of the receiving terminal 20, and when no data packet arrives for a certain period, m acknowledgment packets are transmitted in one round. May be adjusted to transmit.

  In the reception confirmation packet, as in the case of TCP reception confirmation, the sequence number of the last data packet that could be continuously received from the start of communication until the transmission of the acknowledgment packet is described. Therefore, even if an acknowledgment packet is lost in the round, if the subsequent acknowledgment packet is delivered to the transmitting terminal, the reception status notified by the lost acknowledgment packet can be confirmed.

  In describing the method of calculating the confirmation response frequency, in the present embodiment, it is defined that each round operates independently. For example, when the last acknowledgment packet confirmation response packet k of round a in FIG. 9 is lost, it is assumed that the data reception confirmation in the a round cannot be performed by the acknowledgment packet of the subsequent round a + 1.

Confirmation frequency
Next, a method for calculating the confirmation response frequency in the data communication system according to the second embodiment will be described. In the following, the redundant retransmission data packet occurrence rate is introduced as an index for calculating the optimal acknowledgment frequency.
In FIG. 9, all the acknowledgment packets after the third acknowledgment packet ACK ₁ from the beginning of round a are lost, and all the data packets transmitted after receiving the _second acknowledgment packet ACK ₂ from the beginning are all receiving terminals. 20, the number of redundant retransmission data packets transmitted from the transmission terminal 10 to the reception terminal 20 is (m−3 + 1) × n / m.

Here, since each round operates independently as described above, when the data packet loss rate is P _{L_DT} and the confirmation response loss rate is P _{L_ACK} , (m−3 + 1) × n / m packets The expected value P _RDND3 at which the redundant retransmission data packet is transmitted is expressed by the following equation (9).
P _RDND3 = (m−3 + 1) × n / m × (1−P _{L_DT} ) × (1−P _{L_ACK} ) × P _{L_ACK} ^{(m−3 + 1)} (9)

In Equation (9), the term (1-P _{L_ACK} ) indicates the probability that the acknowledgment packet ACK ₂ is not _lost , and the term P _{L_ACK} ^{(m−3 + 1)} includes the acknowledgment packet ACK ₃ and thereafter. The probability that all acknowledgment packets are lost is shown.
Therefore, if the k-1th acknowledgment packet ACK _{k_1} (k is an integer of 2 ≦ k ≦ m) is not lost and all the _{kth and} subsequent acknowledgment packets ACK _{k to} ACK _m are lost, the redundancy at that time The number of retransmitted data packets N _RDNDk is expressed by the following equation (10).
N _RDNDk = (m−k + 1) × n / m × (1−P _{L_DT} ) × (1−P _{L_ACK} ) × P _{L_ACK} ^{(m−k + 1)} (10)

Further, since k = 1 corresponds to a case where all the acknowledgment packets are lost, the number of redundant retransmission data packets N _RDND1 is expressed by the following equation (11).
N _RDND1 = m × n / m × (1-P _{L_DT} ) × (1-P _{L_ACK} ) × P _{L_ACK} ^m (11)

Therefore, in round a, the number of redundant retransmission data packets N _RDND when m acknowledgment packets are transmitted for n transmission data packets is expressed by the following equation (12).
N _RDND = Σ _{k = 2} ^m {(m−k + 1) × n / m × (1-P _{L_DT} ) × (1-P _{L_ACK} ) × P _{L_ACK} ^{(k−m + 1)} } + k × n / m × ( 1-P _{L_DT} ) × (1-P _{L_ACK} ) × P _{L_ACK} ^k
= N / m × (1−P _{L —DT} ) × Σ _{k = 1} ^m {(m−k + 1) × P _{L —ACK} ^k } (12)

By dividing both sides of this equation (12) by n, the redundant retransmission packet data occurrence rate P _RDND that represents the ratio of the number of redundant retransmission data packets generated for n transmission data packets in round a is (13)
P _RDND = 1 / m × (1-P _{L —DT} ) × Σ _{k = 1} ^m {(m−k + 1) × P _{L —ACK} ^k } (13)
Therefore, the acknowledgment frequency F _ACK in round a can be calculated by substituting the equation obtained by solving equation (13) for m into the relational expression of F _ACK = m / n.

[Target redundant retransmission data packet rate]
Next, a method for calculating the target redundant retransmission data packet occurrence rate will be described.
A method of estimating the target redundant retransmission data packet occurrence rate from the past communication result between the transmitting and receiving terminals based on the equation (13) can be considered. That is, when the average value of the data packet loss rate is P _{L_DT_AVG} , the average value of the acknowledgment response loss rate is P _{L_ACK_AVG,} and the average value m _{AVG of the} number of response confirmation packets transmitted per round, the target redundant retransmission data packet The occurrence rate P _RDND is expressed by the following equation (14) based on the equation (13).
P _RDND = 1 / m _AVG × (1−P _{L_DT_AVG} ) × Σ _{k = 1} ^m {(m _AVG −k + 1) × P _{L_ACK} ^k } (14)

As for the target redundant retransmission data packet occurrence rate, a fixed value calculated in advance based on past communication results may be used, but the data packet loss rate average value calculated at regular intervals during data communication, The target redundant retransmission data packet occurrence rate may be sequentially updated during data communication using the average value of the acknowledgment response loss rate and the average number of transmission response acknowledgment packets m _AVG . Thereby, even when the data communication status changes, the target redundant retransmission data packet occurrence rate appropriate for the data communication status at that time can be obtained.

Further, when the data packet loss rate and the acknowledgment response loss rate increase / decrease with a change width equal to or greater than the respective threshold values, instead of the average transmission response confirmation packet number m _AVG in one round in the above formula (14), The target redundant retransmission data packet occurrence rate P _RDND may be calculated by the following equation (15) using the number m of transmission response confirmation packets of the most recent one round. Note that β is a constant.
P _RDND = 1 / m × (1−P _{L_DT_AVG} ) × P _{L_ACK_AVG} × β (15)

  When a failure occurs in a node located on the data communication path between the transmission terminal 10 and the reception terminal 20 and a large amount of data packets are temporarily lost, the data packet loss rate and confirmation response before and after the failure Loss rates can fluctuate significantly. In such a case, the confirmation response frequency rapidly increases and the number of confirmation response packets increases, leading to a rapid increase in processing load on the transmission terminal 10 and the reception terminal 20. Therefore, if the target redundant retransmission data packet occurrence rate is calculated using the most recent one round transmission data packet N, the change width of the target redundant retransmission data packet occurrence rate can be suppressed, and the transmission terminal 10 and the reception terminal A sudden increase in processing load at 20 can be avoided.

  In addition, when an upper limit and a lower limit are set as appropriate ranges for the target redundant retransmission data packet occurrence rate, and the newly calculated target redundant retransmission data packet occurrence rate is out of the appropriate range consisting of these upper and lower limits, As the new target redundant retransmission data packet occurrence rate, an upper limit value or a lower limit value of an appropriate range may be used. As a result, even if the data packet loss rate and the acknowledgment loss rate fluctuate greatly, the extreme target redundant retransmission data packet occurrence rate and the acknowledgment frequency are not calculated, and stable retransmission control can be maintained. It becomes. At this time, the upper limit value and lower limit value of the confirmation response frequency corresponding to the upper limit value and the lower limit value of the target redundant retransmission data packet occurrence rate are calculated in advance, and compared with the newly calculated confirmation response frequency, You may make it suppress the fluctuation | variation of a response frequency.

  The target redundant retransmission data packet occurrence rate may be calculated according to the number of hops between transmitting and receiving terminals. The number of hops is obtained by the number of nodes plus 1 through which data packets and acknowledgment packets pass in the data communication path between the transmitting terminal 10 and the receiving terminal 20. As the number of passing nodes, that is, the number of hops increases, the data packet loss rate and the confirmation response loss rate may increase due to the influence of other traffic. Therefore, if a function is derived in advance as a rule of thumb from the past communication result, for example, the relationship between the number of hops and the target redundant retransmission data packet occurrence rate, the data between the transmitting terminal 10 and the receiving terminal 20 The target redundant retransmission data packet occurrence rate according to the number of hops regarding the communication path can be obtained from the above function.

[Effects of Second Embodiment]
As described above, according to the present embodiment, a plurality of acknowledgment packets are returned in one round, and data packets that can be continuously received from the start of data communication are notified each time with these acknowledgment packets. The present invention can also be applied to the communication operation as in the first embodiment, and the same effects as described above can be obtained.

[Third Embodiment]
Next, a data communication system according to the third embodiment of the present invention will be described with reference to FIG. 10 and FIG. FIG. 10 is a block diagram showing a configuration of a transmission terminal used in the data communication system according to the third embodiment of the present invention. FIG. 11 is a block diagram showing a configuration of a receiving terminal used in the data communication system according to the third embodiment of the present invention.

  In the first embodiment, the case where data communication is performed by forming one communication channel between the transmission terminal 10 and the reception terminal 20 has been described as an example. In the present embodiment, a case where a session is established between the transmission terminal 10 and the reception terminal 20 and data communication is performed using a plurality of channels formed in the session in parallel will be described as an example.

  When performing data communication as described in the first embodiment for each of a plurality of applications between the transmission terminal 10 and the reception terminal 20, the transmission terminal 10 and the reception terminal 20 are similar to those described above for each of these applications. When a configuration is prepared, it is necessary to perform packet retransmission control using an acknowledgment packet for each application. For this reason, as the number of applications increases, acknowledgment packet transmission also increases linearly.

  In the present embodiment, in order to reduce the transmission of the acknowledgment packet, a communication channel corresponding to each application is formed, and transmission data of each application is transferred as a data packet of each communication channel. The confirmation responses are aggregated and notified in one confirmation response. As a result, the number of acknowledgment packet transmissions can be reduced.

[Sending terminal]
Next, the configuration of a transmission terminal used in the data communication system according to the third embodiment of the present invention will be described with reference to FIG.
The transmission terminal 10 is composed of information communication equipment such as a personal computer and a mobile phone terminal as a whole, and as a functional block, a plurality of channel processing units 60 provided for each communication channel corresponding to each application, and these channels A session control unit 50 provided in common to the processing unit 60 is provided.

  Each channel processing unit 60 has the same configuration, and a transmission data storage unit 61 and a channel packet creation unit 62 are provided as main functional units.

The transmission data storage unit 61 has a function of temporarily storing transmission data output from a corresponding application (not shown).
The channel packet creation unit 62 has a function of creating a data packet for the communication channel by adding a header to the transmission data acquired from the transmission data storage unit 61 and outputting the data packet to the session control unit 50. At this time, the header of the data packet includes channel identification information for uniquely identifying the communication channel, a sequence number for the communication channel for uniquely identifying the transmission order of the data packet within the communication channel, and destination communication. The channel is described.

  The session control unit 50 includes a session packet creation unit 51, a packet transmission unit 52, a packet reception unit 53, a retransmission control unit 54, and an acknowledgment response rate calculation unit 55 as main functional units.

  The session packet creation unit 51 adds a header describing the sequence number and destination information for the session uniquely identified as the data packet transmitted from the transmission terminal 10 to the data packet output from the channel processing unit 60 of each channel. To the packet transmission unit 52, the function of outputting the data packet to the retransmission control unit 54 in preparation for retransmission of the data packet, and the confirmation response loss rate information notified from the confirmation response loss rate calculation unit 55 , A function of generating a confirmation response loss rate information packet by adding a header and outputting the packet to the packet transmission unit 52.

  At this time, in the header of the confirmation response loss rate information packet, in addition to the address information used for packet transfer in the communication network 30, an identifier indicating that the packet is a packet for loss rate information notification, and the confirmation response loss A sequence number for uniquely identifying the transmission order of rate information packets is described.

The packet transmission unit 52 has a function of transmitting the data packet and confirmation response loss rate information packet output from the session packet creation unit 51 and the retransmission data packet output from the retransmission control unit 54 to the communication network 30. ing.
The packet receiving unit 53 has a function of receiving an acknowledgment packet from the communication network 30, a function of notifying the sequence number described in the header of the received acknowledgment packet to the acknowledgment loss rate calculating unit 55, and the confirmation response A function of transferring the packet to the retransmission control unit 54.

The retransmission control unit 54 has a function of holding the data packet output from the session packet creation unit 51, a function of deleting the transmission data packet when the reception confirmation for the data packet is accepted, and a reception confirmation. If the data packet is not recognized, it has a function of outputting the data packet to the packet transmission unit 52 in order to retransmit the data packet.
For the reception confirmation, the acknowledgment packet received from the receiving terminal 20 is acquired from the packet receiving unit 14, and each transmitted data packet is referred to by referring to the sequence number of each data packet described in the acknowledgment packet. The reception success or failure at the receiving terminal 20 is confirmed.

  Since the acknowledgment packet contains the sequence numbers of the data packets received by the receiving terminal 10 among the data packets transmitted from the transmitting terminal 10, the reception can be confirmed based on these sequence numbers. Therefore, among the data packets temporarily held by the retransmission control unit 54, the data packets that match these sequence numbers are deleted. On the other hand, a data packet having a sequence number not described in the acknowledgment packet is output to the packet transmitter 13 for retransmission. In addition, if an acknowledgment packet for the data packet does not arrive after a certain time has elapsed since the transmission of the data packet, all the data packets temporarily held by the retransmission control unit 54 are sent for retransmission. It is output to the packet transmitter 52.

  The confirmation response loss rate calculation unit 55 is a loss such as lost or discarded among the confirmation response packets sent back from the receiving terminal 20 based on the reception status composed of the sequence number of each confirmation response packet output from the packet reception unit 53. Has the function of calculating the rate of acknowledgment packets that have not been delivered to the transmission terminal 10 as the acknowledgment response loss rate, and the function of notifying the session packet creation unit 51 of the calculated acknowledgment response loss rate. . In this case, the confirmation response loss rate may be calculated for every fixed time or for every fixed number of confirmation response packets.

  Among the functional units of the transmission terminal 10, the transmission data storage unit 61 includes a storage device such as a hard disk or a memory. The packet transmission unit 52 and the packet reception unit 53 are configured by dedicated communication circuit units. Further, the channel packet creation unit 62, the session packet creation unit 51, the retransmission control unit 54, and the confirmation response loss rate calculation unit 55 are configured by an arithmetic processing unit. This arithmetic processing unit has a CPU and its peripheral circuits, and executes various programs related to data communication by executing the program read from the storage unit (not shown), thereby causing the hardware and the program to cooperate with each other. Realize the part.

[Receiving terminal]
Next, the configuration of a receiving terminal used in the data communication system according to the third embodiment of the present invention will be described with reference to FIG.
The receiving terminal 20 as a whole is composed of information communication equipment such as a personal computer or a mobile phone terminal, and as a functional block, a plurality of channel processing units 80 provided for each communication channel corresponding to each application, and these channels A session control unit 70 provided in common to the processing unit 80 is provided.

  Each channel processing unit 80 has the same configuration, and a channel confirmation response unit 81 and a reception data storage unit 82 are provided as main functional units.

The channel confirmation response unit 81 acquires the channel identification information of the data packet and the sequence number for the communication channel from the header of the received data packet output from the session control unit 70, and notifies the session control unit 70 of the channel identification information. And a function of deleting the header assigned by the channel packet creation unit 62 of the transmission terminal 10 from the data packet and storing it in the received data storage unit 82.
The reception data storage unit 82 has a function of storing the reception data extracted by the channel confirmation response unit 81 and outputting it to an application (not shown).

  The session control unit 70 includes a packet reception unit 71, a session confirmation response unit 72, a packet creation unit 73, a packet transmission unit 74, a loss rate acquisition unit 75, and a confirmation response frequency determination unit 76 as main functional units. ing.

  The packet receiving unit 71 notifies the loss rate acquiring unit 75 of a function of receiving a data packet and an acknowledgment response loss rate information packet from the communication network 30 and a sequence number for a session described in the header of the received data packet. A function of outputting the data packet to the channel processing unit 80 of the communication channel corresponding to the channel identification information described in the header, and a function of outputting the received acknowledgment response loss rate information packet to the loss rate acquiring unit 75 Have.

  The session confirmation response unit 72 acquires and retains the channel identification information and sequence number notified from each channel processing unit 80 and the confirmation response frequency notified from the confirmation response frequency determination unit 76. A function of notifying the packet creation unit 73 of each channel identification information and sequence number.

  FIG. 12 is an explanatory diagram showing creation of an acknowledgment packet. When the confirmation response frequency notified from the confirmation response frequency determining unit 76 is 1 / N, the number of data packets that can be notified of reception confirmation by one confirmation response packet is N. Therefore, when the channel identification information and sequence numbers for confirmation of reception from each communication channel are N data packets, the session confirmation response unit 72 notifies the packet creation unit 73 of these channel identification information and sequence numbers.

The packet creation unit 73 uniquely identifies the acknowledgment packet in which the channel identification information and the sequence number notified from the session acknowledgment unit 72 are described, and the transmission order of the acknowledgment packet is uniquely identified in this acknowledgment packet. And a function of assigning a header describing address information used for packet transfer in the communication network 30 and transferring it to the packet transmission unit 74.
The packet transmission unit 74 has a function of transmitting the confirmation response packet output from the packet creation unit 73 to the communication network 30.

  Data packet transmitted from the transmission terminal 10 via each communication channel based on the reception status of the data packet of each communication channel, which consists of the sequence number for the session output from the loss rate acquisition unit 75 and the packet reception unit 71 Among them, a function of calculating the ratio of data packets that have not been delivered to the receiving terminal 20 due to loss such as loss or discard as a data packet loss rate, and the calculated data packet loss rate to the confirmation response frequency determination unit 76 And a function of acquiring an acknowledgment loss rate from the acknowledgment response rate information packet output from the packet receiving unit 71 and notifying the acknowledgment rate determining unit 76 of the acknowledgment response rate.

  The confirmation response frequency determining unit 76 includes a data packet loss rate and a confirmation response loss rate notified from the loss rate acquisition unit 75, a preset redundant retransmission data packet generation amount or a target value of the redundant retransmission data packet generation rate, In other words, based on the target redundant retransmission data packet generation amount or the target redundant retransmission data packet generation rate, a function of calculating an acknowledgment frequency indicating the frequency of the acknowledgment packet to be returned from the receiving terminal 20 to the transmitting terminal 10, and A function of notifying the session confirmation response unit 72 of the confirmation response frequency.

  Of the functional units of the receiving terminal 20, the received data storage unit 82 includes a storage device such as a hard disk or a memory. Further, the packet receiving unit 71 and the packet transmitting unit 74 are composed of dedicated communication circuit units. Further, the channel confirmation response unit 81, the session confirmation response unit 72, the packet creation unit 73, the loss rate acquisition unit 75, and the confirmation response frequency determination unit 76 are configured from an arithmetic processing unit. This arithmetic processing unit has a CPU and its peripheral circuits, and executes various programs related to data communication by executing the program read from the storage unit (not shown), thereby causing the hardware and the program to cooperate with each other. Realize the part.

[Operation of Third Embodiment]
Next, the operation of the data communication system according to the third embodiment of the present invention will be described with reference to FIG. 13 and FIG. FIG. 13 is a flowchart showing the confirmation response frequency calculation process of the data communication system according to the third embodiment of the present invention. FIG. 14 is a flowchart showing an acknowledgment packet transmission process of the data communication system according to the third embodiment of the present invention.
Below, the transmission operation | movement of an acknowledgment packet is demonstrated as operation | movement of the data communication system concerning this embodiment. Other operations related to the data communication system according to the present embodiment are the same as those in the first embodiment, and a detailed description thereof is omitted here.

First, the data communication operation of the data communication system according to the third embodiment of the present invention will be briefly described.
In the transmission terminal 10, the channel packet creation unit 62 of each channel processing unit 60 creates individual data packets from the transmission data of the communication channel and uniquely identifies the transmission order of the data packets in the communication channel. A sequence number for the communication channel and channel identification information indicating the communication channel are assigned.
Thereafter, in the session packet creation unit 51 of the session control unit 50, a sequence number for the session that is uniquely identified as the data packet transmitted from the transmission terminal 10 is given to the data packet from each channel processing unit 60, and the reception terminal Send to 20

In the receiving terminal 20, the packet receiving unit 71 acquires channel identification information from the header of the received data packet, and outputs the data packet to the channel processing unit 80 of the communication channel corresponding to this channel identification information. In response to this, the channel confirmation response unit 81 of each channel processing unit 80 acquires the channel identification information acquired from the data packet and the sequence number for the communication channel, and notifies the session confirmation response unit 72 of the channel identification information.
In this way, the reception status of data packets in each communication channel is aggregated to the session confirmation response unit 72, and the channel identification information and sequence are determined according to the confirmation response frequency notified from the confirmation response frequency determination unit 76. The number is written in the confirmation response packet and transmitted to the transmission terminal 10.

The retransmission control unit 15 of the transmission terminal 10 refers to the channel communication sequence number and channel identification information described in the acknowledgment packet received by the packet reception unit 53, and retransmits corresponding to the sequence number and channel identification information. Delete the data packet. If there is a sequence number for which reception has not been confirmed, a data packet corresponding to the sequence number and channel identification information is output to the packet transmitter 13.
If the acknowledgment packet does not arrive before a certain time has elapsed since the transmission of the data packet, the retransmission control unit 15 outputs all the held data packets to the packet transmission unit 13 and communicates from the packet transmission unit 13. Retransmit to network 30.

Next, the confirmation response frequency determination operation will be described with reference to FIG.
In response to the arrival of the confirmation response loss rate calculation timing, the transmission terminal 10 calculates the confirmation response loss rate by the confirmation response loss rate calculation unit 55 in parallel with the data communication operation (step 200). The session packet creation unit 51 creates an acknowledgment loss rate information packet describing the calculated acknowledgment response loss rate, and transmits the packet from the packet transmission unit 52 to the communication network 30.

The receiving terminal 20 receives the confirmation response loss rate information packet from the communication network 30 through the packet receiving unit 71, and acquires the confirmation response loss rate from the confirmation response loss rate information packet through the loss rate acquisition unit 75 (step 201). .
In addition, the reception terminal 20 uses the loss rate acquisition unit 75 for the session of each data packet output from the packet reception unit 71 in parallel with the data communication operation according to the arrival of the data packet loss rate calculation timing. The loss rate of the data packet is calculated based on the reception status consisting of the sequence numbers (step 202).

Next, the confirmation response frequency determination unit 76 calculates the confirmation response frequency from the data packet loss rate and the confirmation response loss rate acquired by the loss rate acquisition unit 75 and a preset target redundant retransmission data packet rate. Then, the session confirmation response unit 72 is notified (step 203).
Thereafter, the session confirmation response unit 72 notifies the packet creation unit 73 of the sequence number and channel identification information notified from the channel processing unit 80 based on the confirmation response frequency notified from the confirmation response frequency determination unit 76. The packet creation unit 73 creates an acknowledgment packet that describes the sequence number and the channel identification information, and transmits the packet from the packet transmission unit 74 to the communication network 30 (step 204).

Next, an acknowledgment packet transmission process will be described with reference to FIG.
The session confirmation response unit 72 of the receiving terminal 20 acquires the confirmation response frequency from the confirmation response frequency determination unit 76, and determines the number of waiting packets until the next transmission of the confirmation response packet based on, for example, the above-described equation (1). Calculate (step 210).
Subsequently, based on the sequence number of the received data packet notified from each channel processing unit 80, the session confirmation response unit 72 transmits the data packet of the entire session transmitted after the data packet notified by the previous confirmation response packet. The number of packets is calculated (step 211).

  Here, when the number of transmission packets reaches the number of standby packets (step 212: YES), the sequence number and channel identification information held so far are notified to the packet creation unit 73. In response, the packet creation unit 73 creates a new acknowledgment packet common to each channel, and transmits the packet from the packet transmission unit 74 to the transmission terminal 10 (step 213).

[Effect of the third embodiment]
As described above, in this embodiment, by summing the reception status of data packets that arrived in parallel via a plurality of communication channels formed between the transmission terminal and the reception terminal, the loss of these communication channels as a whole. Rate as the data packet loss rate, and the acknowledgment frequency for the entire communication channel based on the data packet loss rate and the acknowledgment loss rate and the target amount of redundant retransmission data packet generation or redundant retransmission data packet generation rate And an acknowledgment packet for the entire data packet received from the transmitting terminal via each communication channel is returned to the transmitting terminal based on the frequency of the acknowledgment response.

As a result, when data communication as described in the first embodiment is performed for each of a plurality of applications between a transmission terminal and a reception terminal, confirmation confirmation of individual communication channels corresponding to these applications is performed as one confirmation. It is possible to collect and notify in response.
For this reason, compared to the case where the first embodiment is applied to each of these communication channels, the number of transmissions of acknowledgment packets can be greatly reduced, and a network or a transmission / reception terminal that is generated according to the loss of acknowledgment packets. It is possible to suppress an increase in processing load and a reduction in communication efficiency.

[Extended embodiment]
In the above description, the case where the second embodiment is applied to the first embodiment has been described as an example. However, the second embodiment may be applied to the third embodiment.
Moreover, although each above embodiment demonstrated as an example the data communication system with which the transmission terminal and the receiving terminal were connected by the wired data communication path, it is not limited to this, A wireless data communication path is used. The present invention can be applied to the connected data communication system in the same manner as described above, and the same operation and effect can be obtained.

  Each embodiment is applicable not only to TCP but also to other communication protocols such as UDP. In particular, for a communication protocol in which the reception confirmation response function is not stipulated as a standard specification such as UDP, a reception confirmation response function equivalent to TCP may be added, for example.

It is a block diagram which shows the structure of the data communication system concerning the 1st Embodiment of this invention. It is explanatory drawing which shows the calculation method of a packet loss rate. It is explanatory drawing which shows the number of reception data packets expectation. It is explanatory drawing which shows the number of resending data packet expectation. It is explanatory drawing which shows the number of redundant retransmission data packets expected value. It is a flowchart which shows the confirmation response frequency calculation process of the data communication system concerning the 1st Embodiment of this invention. It is a flowchart which shows the confirmation response packet transmission process of the data communication system concerning the 1st Embodiment of this invention. It is explanatory drawing which shows the example of a confirmation response frequency determination process timing. It is a sequence diagram which shows the data communication operation | movement of the data communication system concerning the 2nd Embodiment of this invention. It is a block diagram which shows the structure of the transmission terminal used with the data communication system concerning the 3rd Embodiment of this invention. It is a block diagram which shows the structure of the receiving terminal used with the data communication system concerning the 3rd Embodiment of this invention. It is explanatory drawing which shows creation of an acknowledgment packet It is a flowchart which shows the confirmation response frequency calculation process of the data communication system concerning the 3rd Embodiment of this invention. It is a flowchart which shows the confirmation response packet transmission process of the data communication system concerning the 3rd Embodiment of this invention. It is a sequence diagram which shows data packet resending operation | movement when an acknowledgment packet is lost.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Transmission terminal, 11 ... Transmission data storage part, 12 ... Packet preparation part, 13 ... Packet transmission part, 14 ... Packet reception part, 15 ... Retransmission control part, 16 ... Confirmation response loss rate calculation part, 20 ... Reception terminal, DESCRIPTION OF SYMBOLS 21 ... Packet receiving part, 22 ... Confirmation response part, 23 ... Received data storage part, 24 ... Packet preparation part, 25 ... Packet transmission part, 26 ... Loss rate acquisition part, 27 ... Confirmation response frequency determination part, 30 ... Communication network , 50 ... session control unit, 51 ... session packet creation unit, 52 ... packet transmission unit, 53 ... packet reception unit, 54 ... retransmission control unit, 55 ... confirmation response loss rate calculation unit, 60 ... channel processing unit, 61 ... transmission Data storage unit 62 ... channel packet creation unit 70 ... session control unit 71 71 packet reception unit 72 72 session confirmation response unit 73 ... packet creation unit 7 ... packet transmission unit, 75 ... loss rate acquiring unit, 76 ... acknowledgment frequency determining unit, 80 ... channel processing unit, 81 ... channel acknowledgment unit, 82 ... reception data storage unit.

Claims (11)

Including a transmitting terminal and a receiving terminal connected via a communication network, the receiving terminal returns an acknowledgment packet indicating the reception status of the data packet received from the transmitting terminal to the transmitting terminal, and the transmitting terminal When an undelivered data packet is retransmitted according to the reception status notified by the acknowledgment packet, and an acknowledgment packet related to the data packet is not received from the receiving terminal within a predetermined time from the transmission of the data packet A data communication system for retransmitting all of the data packets,
The transmitting terminal calculates an acknowledgment loss rate related to an acknowledgment packet that did not reach the transmitting terminal based on the reception status of the acknowledgment packet, and calculates an acknowledgment response loss rate that notifies the receiving terminal of the acknowledgment response loss rate Part
The receiving terminal is
A data packet loss rate calculation unit that calculates a data packet loss rate related to a data packet that did not reach the receiving terminal based on the reception status of the data packet, and that acquires the confirmation response loss rate notified from the transmitting terminal;
The data packet loss rate and the acknowledgment response loss rate, and the amount of redundant retransmission data packets generated or the rate of redundant retransmission data packets regarding the data packets that are redundantly retransmitted from the transmitting terminal despite reaching the receiving terminal An acknowledgment frequency determining unit for determining an acknowledgment frequency indicating the frequency of the acknowledgment packet to be returned based on a target value;
A data communication system comprising: a confirmation response unit that returns the confirmation response packet to the transmission terminal based on the confirmation response frequency. The data communication system according to claim 1, wherein
The acknowledgment frequency determining unit, the data packet loss rate P _{L_DT,} the acknowledgment loss rate P _{L_ACK,} if the target value of the redundant retransmission data packet generation amount was N _RDND, the acknowledgment frequency P _ACK A data communication system, which is calculated by the following formula: P _ACK = (1−P _{L —DT} ) × P _{L —ACK} / N _RDND The data communication system according to claim 1, wherein
The acknowledgment frequency determining unit, the data packet loss rate of the mean value P _{L_DT_AVG,} if the average value of the acknowledgment loss rate was P _{L_ACK_AVG,} the target value N _RDND of the redundant retransmission data packet generation amount, the following A data communication system characterized by calculating by the following formula: N _RDND = (1−P _{L_DT_AVG} ) × P _{L_ACK_AVG} The data communication system according to claim 3,
When the data packet loss rate fluctuates more than the first reference fluctuation range, the confirmation response frequency determination unit uses the data packet loss rate after the change instead of the average value of the data packet loss rate. When the target value of the redundant retransmission data packet generation amount is calculated and the acknowledgment loss rate fluctuates more than the second reference fluctuation range, the acknowledgment loss rate after the fluctuation is replaced with the average value of the acknowledgment loss rate A target value of the redundant retransmission data packet generation amount is calculated by using the data communication system. The data communication system according to claim 1, wherein
The confirmation response frequency determining unit sequentially notifies the reception status of the n (n is an integer of 2 ≦ n) data packets using m (m is an integer of 1 ≦ m <n) pieces of the confirmation response packets. And if each of these acknowledgment packets includes the reception status of the data packets that have reached the receiving terminal so far among the n data packets, the data packet loss rate is set to P _{L_DT} , the redundant retransmission data when the acknowledgment loss rate when all the acknowledgment packets after k (k is an integer of 1 ≦ k ≦ m) or later is _lost is P _{L_ACK} ^{(m−k + 1)} The target value P _RDND of the packet occurrence rate is _calculated by the following equation: P _RDND = 1 / m × (1−P _{L —DT} ) × Σ _{k = 1} ^m {(m−k + 1) × P _{L_ACK} ^k } A data communication system. The data communication system according to claim 1, wherein
The data communication system, wherein the confirmation response frequency determining unit calculates a target value of the redundant retransmission data packet generation amount based on the number of nodes that relay-connect between the transmitting terminal and the receiving terminal. The data communication system according to claim 1, wherein
The data packet loss rate calculation unit totalizes the reception status of the data packets that arrived in parallel via a plurality of communication channels formed between the transmission terminal and the reception terminal. The loss rate at is calculated as the data packet loss rate,
The acknowledgment frequency determining unit determines an acknowledgment frequency in the entire communication channel based on the data packet loss rate and the acknowledgment loss rate, and a target value of the redundant retransmission data packet generation amount,
The confirmation response unit returns the confirmation response packet for the entire data packet received from the transmission terminal via each communication channel to the transmission terminal based on the confirmation response frequency. Including a transmitting terminal and a receiving terminal connected via a communication network, the receiving terminal returns an acknowledgment packet indicating the reception status of the data packet received from the transmitting terminal to the transmitting terminal, and the transmitting terminal When an undelivered data packet is retransmitted according to the reception status notified by the acknowledgment packet, and an acknowledgment packet related to the data packet is not received from the receiving terminal within a predetermined time from the transmission of the data packet A data communication terminal used as the receiving terminal in a data communication system for retransmitting all of the data packets,
A data packet loss rate for calculating a data packet loss rate for a data packet that has not arrived at the receiving terminal based on the reception status of the data packet and for obtaining an acknowledgment response rate for the acknowledgment packet notified from the transmitting terminal A calculation unit;
The data packet loss rate and the acknowledgment response loss rate, and the amount of redundant retransmission data packets generated or the rate of redundant retransmission data packets regarding the data packets that are redundantly retransmitted from the transmitting terminal despite reaching the receiving terminal An acknowledgment frequency determining unit for determining an acknowledgment frequency indicating the frequency of the acknowledgment packet to be returned based on a target value;
A data communication terminal comprising: a confirmation response unit that returns the confirmation response packet to the transmission terminal based on the confirmation response frequency. In a data communication system including a transmission terminal and a reception terminal connected via a communication network, the reception terminal returns an acknowledgment packet indicating a reception status of a data packet received from the transmission terminal to the transmission terminal, The transmitting terminal resends an undelivered data packet according to the reception status notified by the confirmation response packet, and an acknowledgment packet related to the data packet is transmitted within a predetermined time from the transmission of the data packet. Is a data communication method for resending all of the data packets,
The transmitting terminal calculates an acknowledgment loss rate related to an acknowledgment packet that has not arrived at the transmitting terminal based on the reception status of the acknowledgment packet, and calculates an acknowledgment response rate that notifies the receiving terminal of the acknowledgment loss rate Steps,
A data packet loss in which the receiving terminal calculates a data packet loss rate related to a data packet that has not arrived at the receiving terminal based on a reception state of the data packet, and acquires the confirmation response loss rate notified from the transmitting terminal Rate calculation step;
The reception terminal receives the data packet loss rate and the acknowledgment loss rate, and the amount of redundant retransmission data packets generated or redundant retransmission related to a data packet that is redundantly retransmitted from the transmission terminal despite reaching the reception terminal. An acknowledgment frequency determining step for determining an acknowledgment frequency indicating the frequency of the acknowledgment packet to be returned based on a target value of the data packet occurrence rate;
A data communication method comprising: a confirmation response step in which the reception terminal returns the confirmation response packet to the transmission terminal based on the frequency of the confirmation response. Including a transmitting terminal and a receiving terminal connected via a communication network, the receiving terminal returns an acknowledgment packet indicating the reception status of the data packet received from the transmitting terminal to the transmitting terminal, and the transmitting terminal When an undelivered data packet is retransmitted according to the reception status notified by the acknowledgment packet, and an acknowledgment packet related to the data packet is not received from the receiving terminal within a predetermined time from the transmission of the data packet A data communication method for retransmitting all of the data packets, the data communication method used in the receiving terminal,
A data packet loss rate calculation unit calculates a data packet loss rate related to a data packet that has not arrived at the receiving terminal based on a reception status of the data packet, and an acknowledgment response loss related to the confirmation response packet notified from the transmitting terminal. A data packet loss rate calculating step for acquiring a rate;
The acknowledgment frequency determining unit is configured to generate a redundant retransmission data packet generation amount relating to the data packet loss rate and the acknowledgment response loss rate, and a data packet redundantly retransmitted from the transmitting terminal despite reaching the receiving terminal, or An acknowledgment frequency determining step for determining an acknowledgment frequency indicating the frequency of the acknowledgment packet to be returned based on a target value of the occurrence rate of redundant retransmission data packets;
A data communication method, comprising: a confirmation response step in which the confirmation response unit returns the confirmation response packet to the transmission terminal based on the frequency of the confirmation response.   The program which makes the computer of the data communication terminal used as a receiving terminal of a data communication system perform each step of Claim 10.

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